1. Field of the Invention
The present invention relates to photoelectric conversion devices formed using a semiconductor, electronic devices equipped with the photoelectric conversion devices, and methods for manufacturing the photoelectric conversion devices.
2. Description of the Related Art
Photoelectric conversion devices which detect visible light having a wavelength range of from 400 nm to 700 nm are referred to as optical sensors or visible optical sensors. Optical sensors or visible optical sensors are known to be used for, for example, detecting optical signals to reading data, detecting ambient brightness to control operation of electronic devices, and the like.
For example, in cellular phones or television units, optical sensors are used for controlling the luminance of display screens in accordance with the ambient brightness of places where they are set (see Reference 1: Japanese Published Patent Application No. 2002-62856).
FIG. 3A shows the structure of an optical sensor disclosed in Reference 1. A photoelectric conversion layer 1603 is provided over a substrate 1601 between a light reflective electrode 1604b and a light-transmitting electrode 1602 provided with openings 1605 and 1606. The photoelectric conversion layer 1603 including p-i-n junction, the light-transmitting electrode 1602, and the light reflective electrode 1604b are combined to form a diode. That is, a configuration of a two-terminal element is obtained. One external connection terminal is a light reflective electrode 1604a connected to the light-transmitting electrode 1602 through an opening 1607 provided in the photoelectric conversion layer 1603, and the other external connection terminal is the light reflective electrode 1604b. Light is received on the light-transmitting substrate 1601 side, and the light transmitted through the substrate 1601 enters the photoelectric conversion layer 1603.
FIG. 3B illustrates an optical sensor in which a light reflective electrode 1611, a photoelectric conversion layer 1612, and a light-transmitting electrode 1613 are provided in this order over a substrate 1610. The optical sensor has a structure in which light enters the photoelectric conversion layer 1612 from the light-transmitting electrode 1613 side. Through holes are provided in the light reflective electrode 1611 and the photoelectric conversion layer 1612 and openings 1614 and 1615 are provided. So, end portions of the substrate 1610 are separated to prevent a short circuit. The light-transmitting electrode 1613 and a light-transmitting electrode 1619 are electrically isolated by an insulating layer 1616 provided over the photoelectric conversion layer 1612. An external connection terminal 1617 is provided in contact with the light-transmitting electrode 1619, and is electrically connected to the light reflective electrode 1611 in an opening formed in the photoelectric conversion layer 1612. An external connection terminal 1618 is provided in contact with the light-transmitting electrode 1613.
FIG. 3C illustrates a mode in which the optical sensor shown in FIG. 3A is mounted on a wiring substrate 1800. The wiring substrate 1800 and the optical sensor are fixed to each other with a UV-carable resin or a thermosetting resin 1852 such that a wiring 1850 is opposed to the light reflective electrodes 1604a and 1604b which are external connection terminals. The light reflective electrodes 1604a and 1604b are electrically connected to the wiring 1850 through conductive particles 1851. Further, FIG. 3D illustrates a mode in which the optical sensor shown in FIG. 3B is mounted on the wiring substrate 1800. The wiring substrate 1800 is attached to the optical sensor with a conductive material 1853 of cream solder, silver paste, or the like such that the wiring 1850 is opposed to the external connection terminals 1617 and 1618.
The optical sensor shown in FIG. 3C is implemented in a manner in which the optical sensor is attached to the wiring substrate 1800 only at the surface over which the light reflective electrodes 1604a and 1604b are formed. Further, the optical sensor shown in FIG. 3D is implemented in a manner in which the external connection terminals 1617 and 1618 are attached to the wiring substrate 1800 only with the conductive material 1853. However, with such structures, there has been a problem in that when bending stress is applied to the wiring substrate 1800, poor contact would be caused in the terminal area, which may separate the optical sensor from the wiring substrate 1800.